At present, the LED products are widely used in daily life. The LED (light emitting diode) has been gradually replacing the traditional halogen lamp as it has the advantages such as stable property, easy manufacturing and low power consumption. However, in a situation where a high light brightness and efficiency are required, e.g. in surgery, an illuminating apparatus quite matched with the application field is demanded for obtaining the effect of a lamp with uniform and shadowless illumination. Thus, a halogen bulb is still used currently. In view of the disadvantages such as high power consumption of the halogen bulb, the customer desires to obtain a solution capable of replacing the halogen bulb with the LED.